Cellar mobile phones provide an extremely great convenience to communication of the people, and the 2nd generation global mobile communication system (GMS: Global System for Mobile Communication) (Registered Trademark) provides further improvement of communication quality in mobile communication by adopting digital communication techniques. The 3rd generation partnership project (3GPP) as an important organization in the mobile communication field has extensively promoted standardization of the 3rd generation mobile communication technology (3G: The Third Generation) and established a series of communication system standards such as WCDMA (Wide Code Division Multiple Access), HSDPA (High Speed Downlink Packed Access) and HSUPA (High Speed Uplink Packet Access).
In order to address challenges of the wideband access technique and respond to growing demand for new services, the 3GPP has started standardization of the 3G long-term evolution (LTE) since the end of 2004, planning to improve spectrum efficiency and performance of cell-edge users, reduce system delay and provide a higher-speed access service to high-speed mobile users. The improved LTE (LTE-A) technology provides high-speed and excellent-performance services to more mobile users by multiplying data rate and increasing the frequency bandwidth by several times based on the LTE technology.
In the LTE-A system, a multi-user Multiple-Input Multiple-Output (MU-MIMO) technique is supported. That is, in the LTE-A system, a plurality of user equipments (UEs) can be scheduled simultaneously in same-frequency resources. In other words, in the LTE-A system, plural UEs can share frequency resources such as resource blocks. The UEs sharing same frequency resources may be called one coordinated transmission group participating in the MU-MIMO transmission.
In the MIMO system, in order to improve the spectrum efficiency and power user efficiency, there has been proposed an idea of MIMO precoding. In this MIMO precoding, a transmission side can use channel state information (CSI). In a closed-loop downlink MIMO/coordinated multi-point (CoMP) system, CSI required for precoding can be obtained from an uplink feedback from UE.
In an actual system, CSI is divided into following two parts, that is, channel phase information (for example, precoding Matrix indicator (PMI), channel direction information (CDI) or channel covariance) and channel quality information (for example, channel quality indicator (CQI)).
As illustrated in FIG. 1, a precoding section for performing precoding in a conventional base station includes, as an internal configuration, a precoding matrix determining module 101 configured to determine a precoding matrix to use in precoding in the base station, based on a precoding matrix indicator (PMI) reported from a UE and a codebook stored in the base station, a channel quality determining module 102 configured to determine channel quality information to use in precoding in the base station, based on a channel quality indicator (CQI) reported from the UE and a CQI table stored in the base station, and a precoding module 103 configured to perform precoding on data to transmit to the UE based on the determined precoding matrix and channel quality information.